Spray gun



D. J. PEEPS SPRAY GUN July 2l, 19.59

2 Sheets-Sheet 1 Filed March 16, 1956 mm E m D n m L E, .A l Nn U U.

D. J. PEEPS July 21, 1959 SPRAY GUN 2 Sheets-Sheet 2 Filed March 16,1956 JNVENTOR.' J PHP5. a @am .UMA/:17

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United States Patent SPRAY GUN Donald J. Peeps, Rossford, Ohio, assignorto The De Vilbiss Company, Toledo, Ohio, a corporation of OhioApplication March 16, 1956, Serial No. 572,000 6 Claims. (Cl. 239-412)This invention relates to an automatic spray gun, and particularly tosuch a spray gun utilizing compressed air for atomization and forcontrolling the operation of the device.

The situation in the coating ield is in accord with the general trend inmodern industry of more and more operations formerly manually performedbeing handled by self-functioning mechanisms.

There has been a recent expanding development of the use of automaticspray equipment in the application of lubricants in sheet metal formingand stamping presses. Lubrication is needed principally to facilitatethe movement of the metal into its formed shape. It is of furtherbenefit in easing the removal of the punch or die from the finishedrwork.

The spray method has proved superior in several important aspects to thewiping, brushing, and dripping devices previously utilized. Alt is notwasteful of lubricant, directing only enough for the purpose to the areaunder treatment. The distribution by spray is more uniform and selectiveand is therefore more effective.

Other advantages include labor saving, not only in the application, butin reducing or eliminating the time of cleaning `up excess lubricantcollecting on the machines and on the floor which occur with othermethods.

Further, as thelubricant is kept in a closed system inv spray equipmentit remains clean and unadulterated, and no foreign substances injuriousto the work or dies are applied with it. 'Y

Spray equipment for this iield should be as simple Vin design andoperation as possible. It further should function rapidly and in propertiming with the cycles of the press. As spiace is frequently limited, acompact spray gun is necessary and one that will not be adverselyaffected by its proximity to the heat, dirt, and oil accompanying theoperation of the press.

.The object of this invention is the provision of a spray gun to meetthe requirements referred to above as well as others which will beapparent upon reading the following description and referring to thedrawings in which: Figure 1 is a longitudinal vertical section, taken onthe line 1 1 of Figure 2, of a spray gun embodying my invention;

n Figure 2 is a yview of the under side of the spray gun of Figure 1with parts broken away and the inlet connections removed;

Figure 3 is a cross section taken on the line 3-3 of Figure l;

Figure 4 is a similar section taken on the line 4-4 of Figure l;

Figure 5 is a front elevation of the spray gun with the air cap and uidtip removed; and

Figure 6 is an enlarged lengthwise section of the air valve andassociated parts within the spray gun.

Referring to the drawings in more detail, the spray gun has a main bodymember 1, fastened by a series of six bolts 2 to rear body section 3.Opposed cavities 4 and 5 in the adjoining surfaces of the body member 1Patented July 21, 1959 and body section 3 form a diaphragm chamber 6.Di. aphragm 7 is held in place therein having its periphery clampedbetween the two parts of the body.

Coating material enters the spray gun by way of inlet 9 to which it maybe fed under pressure from a supply tank through a hose 10 andconnection 11. Passage 14 to which inlet 9 communicates has a rearwardlyinclined extension 15 leading to the diaphragm chamber 6 on the forwardside of the diaphram 7.

An axially located port 16 in the front wall of the chamber provides apath for the coating material to the fluid tip 17 from which the coatingmaterial is discharged to the atmosphere through outlet 18. A fluidneedle valve 20 governs the flo/w of coating material from outlet 18.The Ineedle valve 20 extends rearwardly through a tubular member 21fixed to the diaphragm 7 by the nut 22.

Clamped on opposite sides of the diaphragm 7 by the nut 22 and ashoulder on member 21 are two similar discs 23 and 24 which strengthenthe diaphragm and prevent undue distortion of it. Disc 24 also serves asa stop in rearward movement of the diaphragm. A spring 25 bearingagainst disc 23 inclines the diaphragm to its rearward positionindicated in dotted lines in Figure 1.

The valve 20 has a snug but slidable iit within the bore of member 21.Threaded into the rear end of member 21 is a hollow extension 26 withits inner chamber 27 closed by plug 28. Within chamber 27 is a spring 29thrust against the enlargement 30 on the end of the fluid needle valve20 extending into the chamber. The spring 29 inclines the valve 20 toits seatei-n-fluid tip 17 when the valve is not drawn from its closedposition by rearward abutting movement of member 21 against enlargement20, such movement accompanying like rearward travel of diaphragm 7.

Cylindrical bore 33, within which hollow extension 26 is conned, isclosed at its rear end by the threaded adjustable stop 34. Lock nut 35holds stop 34 in its selected position for setting the opening limit ofneedle valve 20.

From an air supply hose 37 atomizing air inlet connection 38communicates with passage 39, leading to bore 33. An O-ring 40 acts toprevent leakage of air from the bore past the threads of adjustable stop34.

With rearward travel of the diaphragm 7 air valve 41 is moved from itsseat 42. Air valve 41 is composed of an O-ring 43 held between adjacentannular surfaces 44 and 45, respectively located on the tubular member21 and its hollow extension 26, as shown most clearly in the enlargedview of Figure 6. The surface 44 is forwardly ared to lock the O-ring inplace without severely compressing it.

With air valve 41 drawn from its seat 42, the atomizing air ilows intothe restricted bore 47 and down drilling 48. Then the air travelsforwardly by way of passage 49 leading through the clamped periphery ofdiaphragm 7 into intermediate chamber 50 in the main body member 1.

In vertical channel 54 rising from chamber 50, the air stream is dividedwith one portion entering lateral passage 55 under the throttling actionof valve 56, and the other portion passing forwardly through drillings57 and 58 into the annular chamber 59.

The part of the atomizing air subject to reduction in pressure by valve56, reaches, by way of borings 61, the ring shaped space 62 from whichit iiows through flange ports 63 in fluid tip 17 to arrive at the outletpassage 64 l 3 to be expelled from the annular outlet 69 between thetip-17and air cap 66 for'primary atomizingv actionupon the coatingmaterial issuing from tip 17.

Motivating air for control of the operation of the spray gun entersthrough connection` 70A from hose 71 andA passes from passage 72intodiaphragm chamber 6' on the rear sidev of the diaphragm 7 i Inutilizing the spray gun of this invention it is mounted in positionsingly orinY sets' in association with the forming press or othermachine with-which itis to be employed. The gun is held on a supportingbar or bolt passed through the ported mounting extension 73. The bar maybe part of `any suitable bracket 74.

The coating material, atomizing air and motivating air` supply hoses 10,71, and 37 are connected respectively to inlets 9, 38, and-70. Thecoating material is generally under pressure but may be drawn by thesuction effect of the air discharge from the spray gun nozzle, from anunpressurized receptacle. Inthe latter situation the spring 25 isutilized to impel the diaphragm 7 rearwardly upon venting of themotivating air.

The atomizing air is fromv a source regulated towhatever pressure isrequired for the type of atomization desired and valve 56 is adjusted toprovide the appropriate widthof the fan spray.

The pressure of the motivating air is set to exceed the pressure of thecoating material, that of the spring- 25- or the sum of the twopressures when both are utilized. The motivating air line is equippedwith a three-Way valve actuated by movement-of' the press or insynchro'- nism therewith to alternately vent the motivating air from thespray gun and permit the flow of` air thereto according to the number ofspray gun operations needed with each cycle of the press operation;

With preparations complete to initiate the operationof' the press andthe attached spray gun or set of guns, the needle valve is seated-inthefluid tip 17 and the atomizing air valve 41 is against its seat 42; Thecoating material is within diaphragm chamber 6 with its pressure appliedagainst the forward side of the diaphragm 7; and the motivating airpressure greater'than that of the coating mateiial (and of the spring ifit is` being used) is on the other side of the diaphragm and'- holdingthe diaphragm with the parts carried by it in their-most forwardposition.

The press is then started .with metal stock being usually' fed manually,if the pieces are particularly large, andl likely, automatically, if acontinuousA strip or small blanks are involved.

The spray gun may be directed and arranged for actuation in rapidsequence to coat either or both'tlie lower and upper dies, and inaddition or insteadl the4 its .seat 42, allowing atomizing air to flowpast the valve to air cap 66; and then through abutment With-theenlargement 39, on needle valve2t) moving the needle valve to openposition.

The-extent of opening of valve 2i) -is predetermined -byy adjustment-ofstop 34.. against which the outer end of extension26 strikes. Theopening of'rvalve 20 immediately permits the lubricant'toow fromiluid'tip I7 andbe projected in atomized condition to the surface being;coated.

In order to reduce to a min-- The spray discharge is of extremely shortduration constituting-a momentary puff. ItV is terminatedby rapidreversal of the three-way valve which closes the atmospheric vent andre-establish the communication of the air supply with the spray gunwhereby the diaphragm is forced forwardly letting the iluid needle 20 beseated first through the influence of spring 29 and then seating airvalve 41.

The compact and effective, arrangement of working parts and their modeof function results in exceedingly rapidY and accurate operation ofY thespray gun of this invention.

The. motivatingr air ismaintained at a pressure suficiently high to holdthe diaphragm forwardly and the atomizing air valve firmly` uponitsseat: At the same time the space behind the diaphragm occupied by themotivating air is so small that evacuation and replacement of this airoccurs rapidly.

The" pressure ofthe coating material remains at all timesl bearingagainst the front faceof the diaphragmV ready with no delay toforcefully move the diaphragm rearwardly and, concurrently, open thevalves forthe atomizingairand* coating material.

The' movable elements of the spray gun' structure are alignedV andclosely coupled'which resultsin a body'ofl short length and of moderatecrosswise dimensions. Theenlployment'of` a diaphragm in place-of apiston'elects asavinginspace asV a diaphragm occupies and requires lesslongitudinal room in its operation.l

Another featurel of the design contributingv to the unusual compactnessis the positioning of the diaphragm' chamber, which is necessarily ofconsiderable width,- in4 the middle of the spray gun and the placingy ofthe atomizing air valve, which is much smaller in width, tothe rear ofthe diaphragm chamber.

AA supplemental feature of importance is the air'valve constructioninwhieh the O-ring 43'l constitutes the main valve element. Whileeasilyv assembled the parts are designed to` confine the O-ringwithoutdistortingcompression. This is-accomplished by retaining this elementbetween the flared annular surface 44' on-thetubular' member21' and thestraight surface 45- on the extension 26i The flared surface 44extendsjust-beyond and'over the center'ofthe O-ring with a minor sectorof' the ring protruding/'forwardly to effect the tight sealing valveaction againstthe seat` 42.

It further should be noted that applicants'spray gun has all movingparts internally located withthe body presentirrg a--trim contourwhereby dust, oil; and other impurities present in the surroundingindustrial atmosphere areprevented from reaching the moving parts andareeasily'removed after settling upon the exterior of thel spray gun.

Various changes and modifications may be made-in the embodimentillustrated and described herein without departing from the scope of theinvention as delineated by the followingclaims.

Having thusY described my invention what is claimed as new andl desired'to lue-secured by Letters Patent is:

l. In aspray gun of the type described a main body member, a nozzle atthe forward end of the body member for discharging air atomized coatingmaterial, means providing-a coating material supply inlet adjacent theforward end of the body member and a passage for conveying coatingmaterial under pressure from the supply inlet to the nozzle, other meansproviding a receiving inletfor atomizing air in the body member adjacentthe rear end thereof and also providing a passage for carrying atomizingairffrorn the receiving inlet to the nozzle, a coating material valve, aseat forthe coating material valve in the nozzle against which the valveis normally seated and fromwhich it may be Withdrawn by rearwardmovement, Va second valve and a valve seat therefor against whichv thesecond'lvalve'normally is forwardly seated, said` carrying atomizing airnear the rear end of the body member, a recprocable, pressureresponsive, diaphragm mounted in the mid portion of the body member,connections between the diaphragm and the valves for the coatingmaterial and the -atomzing air, means for applying pressure against theforward face of the diaphragm to move the diaphragm rearwardly andthrough said connections to move the valves from their seats and thusallow coating material and atomizing air to reach and be discharged fromthe nozzle with the air atomizing the coating material, and additionalmeans for applying air Dressure against the rear face of the diaphragmto return the diaphragm forwardly in opposition to the pressure appliedto the forward face of the diaphragm.

2. A spray gun according to claim 1 in which the means applying pressureagainst the forward face of the diaphragm includes 'a chamber within thebody in front of the diaphragm and a branch passage leading to thechamber from. the passage conveying coating material under pressurewhereby coating material reaches and s thrust against the forward faceof the diaphragm.

3. A spray gun according to claim. 1 in which the main body member has aforward section and rearward Section with the coating material inlet inthe forward section, the receiving inlet for atomizing air in therearward section, and the diaphragm peripherally clamped between the twosections.

4. A spray gun according to claim 1 in which an O-ring constitutes themain element of the second valve within the passage for carryingatomizing air and the valve seat therefor provides a at `annular faceagainst which a side of the O-ring has sealing contact when the secondvalve is in closed position.

5. A spray gun according to claim 1 in which the connections between thediaphragm and the valves comprise a positive connection with the airvalve and a lost-motion connection with the material valve.

6. A `spray gun according to claim 1 in which a spring thrust againstthe rear end of the coating material valve normally retains the valve inclosed position against its seat, and the pressure of the atomizing airagainst the rear side of the second valve inclines the second valve toclosed position.

References Cited in the file of this patent UNITED STATES PATENTS2,266,365 Harrison Dec. 16, 1941 2,398,503 Paasche Apr. 16, 19462,479,895 Bahnson Aug. 23, 1949 2,537,051 Grant Jan. 9, 1951 2,645,466Jones July 14, 1953 2,712,457 Kimbra July 5, 1955

